Switched digital communications networks such as Asynchronous Transfer Mode (ATM) and Frame Relay (FR) find particular application in the delivery of multimedia services. In such networks calls are transported across the network architecture by way of switching nodes within the network core. A network management system establishes and controls traffic flow between switching nodes.
Calls or logical links (trunk groups) connected in such a network have various associated call parameters. In the case of ATM, these parameters include Peak Cell Rate (PCR), Sustained Cell Rate (SCR), Maximum Burst Size (MBS), Cell Delay Variance Tolerance (CDVT), Traffic Descriptor, Traffic Policing methods etc. For Frame Relay, such parameters include Committed Information Rate (CIR), Committed Burst Size (Bc), Excess Burst Size (Be), etc. For Frame Relay calls travelling over ATM networks, many of the ATM call parameters are also required. Parameters associated with a call or a trunk group define the expected characteristics of data allowed to flow through them.
As such, these parameters are usually best guesses for the kind of data traffic expected through a call, or a trunk group. Once a call or a trunk group has been provisioned in a network, it might be discovered that some changes are required to some of the parameters in order to make better use of network resources. At this time, there might be customer data flowing through the calls, and hence any disruptions in that flow may be undesirable, or even unacceptable.
Reconfiguration of an already connected call requires a mechanism for the determination of the correctness of the new parameters, propagation of the new parameters to all the relevant network elements, and if there is a failure in propagation of such parameters, recovery from such failures.